Use of Controlled Density Fill in Silo Floors

[Berniedog]

Does anyone have experience in the use of controlled density fill (CDF) where the depth of the fill will be 11'-0"+-? We are designing the Tunnel for the reclaimer and floor slab for a 55' dia.x112' high grain by-product silo. They want the floor slab on the CDF rather than constructing a floor. Load will be 3500 psf.

My questions are:
-What strength of CDF do we need?
-Is there any special concerns about the ring around the perimeter supporting the end of the reclaimer (5k load)?
-Should this be poured in lifts each lift will have a chance to set up (water has no where to go)? CDF will be poured over a matt foundation?

 

[civilperson]

Flowable fill or excavatable fill comes in a variety of strengths, 10 psi to 100 psi. The 3500 psf requirement would lead me to specify 50 psi fill for a safety factor of two. The deepest flowable fill that I have used was around a 72 inch diameter casing, approximately 8' deep. The flowable fill supported construction equipment, (scrapers and motorgraders), after 36 hours. The soils surrounding the fill were permeable, sands and silts.

 

[twinnell]

Conatact a Geotechnical Engineer to discuss this.